Chuck



oct. 11, 1932. D, C, PAGE ET AL 1,881,905

CHUCK Filed June 5, 1931 2 Sheets-Sheet l ct. 11, 1932. D PAGE E11-AL- 1,881,905

CHUCK Filed June 5, 19.31 2 Sheets-Sheet 2 0 Gbmmm D. 5m QM l Patented Oct. 11, 1932 UNITED STATES rsa1-,ecs y PATENT olrlflcvrfg'f" nwrenT c. PACE AND GiTE'EALn n. SCoTT, 0E WORCESTER, MASSACHUSETTS, Assieiiions To THE HEALE MACHINE COMPANY, E WORCESTER, MASSACHUSETTS, A 'Conro- VEATTON 0E MASSACHUSETTS `Application led June 5,

The present invention relates to 'an improvement in work-holding devices or chucks and more especially to chucks which are adapted for holding annular or hollow workpieces in position to permit a grinding or similar operation to be performed on` the internal bore of the workpiece.

The particular utility of the invention is inholding workpieces having exterior cylinl-a drical or co-nical surfaces; each workpiece is l it will be concentric with the exterior surautomatically centered with reference to its external surface and clamped by end pressure in such position so that when the bore of the workpiece is ground to the desired diameter,

faces. l

In the copending application `Serial No. 174,940, tiled by Page, one of the presentapplicants, and Jellicoe, now Patent No. 1,812,-

017, issued J une 30, 1931, a plurality of centering ingers are urged into engagement with the workpiece, to center said workpiece, in response to movement of an operating rod and continued movement of said rod urges clamping members against the workpiece to hold said workpiece, the pressure exerted on 'the workpiece by the centering lingers is increased by this latter movement so that, especially in workpieces of small cross-secgers tends to distort said workpieces to a slight extent. It is one of the objects of the present invention to avoid the distortion and', according to the present invention, a set o centering iingers is arranged to be urged into engagement withl the workpiece in order to center the workpiece in relation with the surface and, after the workpiece has been clamped, the centering fingers are withdrawn from engagement with the workpiece', thereby to avoidV any tendency of the centering fingers to distort the workpiece.

When the draw rod of t-he chuck is actuated by fluid under pressure, as shown forfexample in the copendingv application of H1ghberg Serial No. 99,287, tiled April 2, 1926, now Patent 1,840,841, issued January 12, 1932, the variations in fluid pressure make it diflicult to maintain a constant tension on the draw rod. The resulting variations in tension on the CHUCK 1931.'` seriai No. 542,290.

the chuck, which tend to distort.Z the work- 'Y piece clamped thereby, with the result that the grinding action on the ,workpieceisnot uniform. .'[n` chucks of .the type' shown in the above identified Page and Jellicoe application, this variable tension on the draw rod varies the pressurev ofboth the clamping members and the centering members against the workpiece. Another obj ect of the present invention is to provide 4a chuck having the the advantages of the above constructions but none of the disadvantages.. In the Agrinding cfa workpiece a considerable amount of heat `is generated, thereby causing the workpiece to expand and, ifithe centering lingers are left in contact with the workpiece during the grinding operation, the

workpiece cannot expand evenly whereby the ground Surface. of the workpiece-is uneven when the workpiece is released from the chuck and is cooled to the normal temperature. It will be readily understood that when a workpiece .is held radially by a plurality of immovable ,members and the workpiece becomes heated as a result ofthe grinding operation, the portionsof .the workpiece. between the members will expand radiallyV and the' portions adjacent the'members will be held against radialmovement. by said members so that the workpiece is `distorted during the greater portion of the grinding operation. As the workpiece cools to normal temperature after removal from the chuck, the said workpiece resumes its normal size and shape, withthe result that the sections which were adjacent the holding membersbecome low spots in the nishedsurface of the bore,V

more material having been removed atthese points during the grinding operation. Al`

though the expansion of a workpiece during the grinding is very slight, it is nevertheless,

great enough to cause objectionable low spots in the finished surface unlessthe radial holding lingers are removedv from contact Vwith the workpiecev during the grinding operation.

iov A n ent invention, as above pointedout,the centering fingers are removed from engagement with the workpiece when said workpiece is clamped in the chuck. Furthermore, the clamping members, which are arranged Vto 'be 'actuatedby a draw rod, are mounted 'in such v a manner that when the draw rod has moved the clamping jaws into clamping position, a

- constant clamping pressure isappliedby each jaw without regard to the vforce' eXertedon `the fdrawv rod, thereby permitting :actuation fof=the1d-raw rod, .to clamp the workpiece, by'a .mechanism which does gnot necessarilyprovvide a fconstant force on said draw rod, :as

' by ariiuid under pressure.

The above and-other advantageous features -ofitheinvention will-appear from the fellowing Ydescription taken in connection with the faccompanyin'g ydrawings in which u VfFri'g. lis Sauf-ront elevation of a work-'hold- .ingdeviceembodyifngthe invention.

`2 .is a `:sectional kview alongthe line 2-2 fof Fig. .1 `showing the chuck .in clamping position.

Y k3 is .a sectional Vview similar to Fig. 2 Vvshowing the ichu'ck inV work-centering posittion.y

f sig'. 4 is :a 'sectional 1view similar kto Fig. :2 showing the :clamping and vcentering lingers Ioutof:engagement withtheworkpiece to per- :mit removal of '.-said'workpiece Likeireference characters refer V:to -likefparts ithediii'erent figures.

l Referring io :the drawings,a setv of workcentering gingersfzmdfa set off clamping a-ws, 7together with their soperating devices'iare enclosed .in ascylindrica-l shell =or casingl. Trheflatter .is fastenedat its inner end to a `face plate 12 by .means vof Ascrews 13; .and `the face -plate :2 iis .secured nto a work-rotatingv spindle f4 orf rotation therewith 'by l.cooperatxingfscrew 4threads 5 .on the :plate .and spindle. The :spindle 4 is provided with :axial bore -6 tto receive, and .to rsupport for vlongitudinal movement itherein,fa .draw 'rod 7, the latter `beingradapted, on .movement to the right, fto fopen the-chuck ifor releaselof fthe *workpiece .dimm theifingers and l:the clamping jaws, rand, n upon lmovement to vfthe lett, ftofclose 'the fchuck to clamp' the workpiece therein. The draw V-rod 7 may be :actuated 'in any suitable man- '-ner., as 1by'iiuid under pressure acting yon either. side of' a piston, `not shown, Asuitably 'connected to'sa'idrod. D y

"lzhershell -1 :provides fa-substantially central fheub 8,'onfthe outer surfacefo-f Iwhich isfmountediaaing shaped member 10, attached thereto as by screws `11,-and lhaving =a Yplane outer 'surface which `provides .a solid backing for V'the workpiece a .when said workpiece. .is

clamped in the chuck. The hub 8 is provided with a central bore 12 in which to receive, for axial movement therein, a slidably mounted member 13, the latter having a plurality of radially projecting ears l, three in the con- 1 shown, or'the pivotal rmounting of -cent'ering lingers -l15. Each year 14 supports one of said werk-centering Vlingers 15 at one end thereof o-n a .pivot pinvl passing 'throughrsai'd car and the end of said finger. Each finger' 15 'is forked where the pivot pin l@ passes through it vandthe free end or" said lcentering ingers may lbe varied radially,*inV

order te position' trie lingers :in desired :relation to the workpiece-by adgustment of .the

set screws 20., said screws vbeing Aheld in adusted position by .lock .nuts 211. A Iplurality o1" -studbolts 22,;each Ylizn/'in-ga'coil-spring 23 mounted thereon, extend inwardly axially of the chuck from-:the anei'nber 1.3 jfor purposes which will hereinafter appear.

A member .2e fis received in a bore 25 of ^the member l-i'or axial Yslid-ing'vino-vement therein, andis Arigidly -connected to the end citi-1e drawvfrod ai", `by cooperating screw threads rPhe slidable member 24- has :apertures 2i' through which the -shanks of the .studs 122 entend, lthe coil vsprings 23 engaging the headsio-ffthe .stud bolts-and the inner side of member :Ski/thereby holdingthe member .ingI an aperture 30 Ytherein within which the reduced portion v81 of one of. the clampingv jaw plungers '32 is-sl-idabl-y received. y

Each jaw :plunger '32 is mounted. foraxial .movement fiirhearings 33 provided by the .shell land is provided-at its oirterend with jaw members S secured toi/the end of the .plu nger :by screws 35 and :extending angularly thereto.' A lshoulder 8, formed by the reduction in diameter of'each aw plunger, 'held fagainst the vouter -or right hand side of the ls'lidab'le .member 211 by a Vspring `which encirclesfthe `reduced end portion 31 loli-said jaw .plunger `o-nthe inner side of said `member .24, athe compression -o'f the spr-ingsI being maintained vby van adjustable collar V23d carried fon the {inner-'end ofv lsaid reduced por- -tion.. f l v.

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Movement of theV slidable' member 24V inwardly of the chuck rin response to inward movement of the draw rod 7 moves the clamping jaws from the inoperative 1position of Fig. 4'into the clamping position of Fig. 2 by axial inward movementl of the jaw plungers. During this inward V.movement, the plungers are rotated in order to swing the clamping jaws from the inoperative position of Fig. 4 into a position for engaging the surface of the workpiece, Fig. 2. To procure' this movement a substantially helical cam 39 is provided in the-surfacefof each plunger, and is engaged by the'inner end of one of a series of studs 40, mounted in the shell 1 and held in position by lock nuts 4l,

so that during inward movement of the plunger, engagement of said stud with the cam -procuresv rotary movement of said plunger. A portion of the member y24 extends over the end of the draw rod 7- and provides a cylindrical bearing surface42'on which an annular member 43 is slidably mounted, said member 43 being held loosely in position by a screw 44. Arcuate depressions 45 are provided in the annular member 43 to avoid engagement of said member with the stud bolts22, thereby to` allow free axial movement of said annular mem-VV ber along the bearing surface`42. A lever '46 isr pivotally supportedfina slot 47 in said annular member 43 by a lpivot pin 48; one end of said lever abuts the inner surface of the member 24 and the other end 51`engages a pin 52 slidable axiallyin the member 24, said pin 52 abutting a surface 53 on the inner side of the member 13. It will be seen that sliding movement of the annular member 43 axially of the member 24 toward the right, rocks thelever 46, pressing the pin 52 to the right, thereby to procure a separation of the members 13 and 24 against the pressure of the springs 23.

in setting up the chuck so that the centering lingers will contact the workpiece with sufficient pressure to centralize the same, a member 54, Fig. 2, is threaded into the outer end of the member 24. Movement ofthe draw rod inwardly, with the member 54 in position, moves the member 24 until a flange on the member 54 contacts with a surface 55 provided by the hub 8 in which position the outer end of the member 24 is in the plane of said surface. With the chuck in this position, the free ends of the fingers 15 are adjusted radially by the set screws 2O to bring the work-engaging portions of said lingers into engagement with the workpiece to hold said workpiece so that the bore therein is l concentric with the axis of the chuck. After the fingers are thus properly adjusted the member 54 is removedl and the chuck is ready for use.

The chuck is operated to clamp or release a workpiece a by movement of the i draw `rod 7, lmovement fsaidrod to the leftor inwardly o-fthechuck :acting to clamp vthe A workpiece,and movement of the rod to the right or outwardly actingV toirelease :the clamping jaws from the workpiece. The positions of Figsf4, 3 and2 showlrespectively consecutive positions ofthe centering and clamping members during inward movement ofthe dra-w rod 7,y Fi'gr4'showingthechuck in openposition and F-ig-2inclosed orclamping position.' In the position shown in Fig. 4thedraw rod is moved to :its extreme `out- Ward or right hand position, so that the clamping jaws are. rotated-out of normal clamping position, and the centering fingers are withdrawn radially from' normal center ing position to permit insertionzofa workpiece. fWith the chuck `inlthis.position, the workpiece wis `inserted so that the `inner surface of said workpiece .is in engagement with the outer. plane surface ofrthe ring 10 against which theworkpiece is to be clamped by subsequent inwardn movement of thed'raw rod. Duringthe initial movement ofthe draw rod 7 to the left, from Ithe position of Fig. 4 to the position `of Fig. 3, the 'member 13 moves asa unit withthe memberf24 so that; the centering fingers ,mounted on mem-V ber13 .are urged into 1 engagement 'withz the periphery ofthe` workpiece by the engagement of theV cam surface 18 with the inner end of thead'justable screw 20. 'Since the jaws534 Vare spaced lto aslight extent from the surface of the workpiece against which they are adapted. to clamp, said :j aws having been rotated, during theinitial movement of draw rod 7, fromthe inoperative position of Fig; 4..into alignment with theV surface of`V the workpiece against whichfsaid jaws are adapted to` clamp. It willbe'seen that the inner surface ofthe annular member 42 is spaced `fromV the surface of the .face plate2 in this position (Fig. .3) a distance substantiallyequal to the spacing of the jaw members from the workpiece. Continued inward movement ofthe Vdraw rod'7 beyond the iosition of Fig. 3 brings the clamping jaws into engagement with `thelsurface of the work-- piece with vsufficif-xnt v`pre'ssureito hold the vworkpiece in position against sliding movement, and moves the annular *member 42 into engagement with the surface of the face plate, the centering 'fingers being resilientiy maintained against the workpiece by compression of the springs 23. :After the annu- V.lar member'42contacts the facie plate,. con'.- .y tinuediinward' movement of. the draw' rod'.l 7.'

' pin 48.,.toward2. the.' right whereby.I the meme ber 13' is: urged'. outwardliy ofy the' chuck against the action: of thespringsf23,the centering. fingers being' urged'. outwardly' therefwi-th; and outof engagement withA the' worklpiece'. During this latter inwvard-movement ofthe draw rod, the'inner side-'surface'.ofthe member 24.4 is brought into engagement with they annular" member. 42'v (which is held against. movement by* engagement with. the face plate 2) so: that4 further inward; move"- ment of thedrawv rod? isipreventedgand the member 24 iss-held in fixed: position.- within the. chuck. regardless. of the4 tensioni .exerted on thel draw' rod, sufficient tensionrbeing maintained to: hold' said member". 24 in' posi'- tionagainst the annular'mem'ber 42;. During thesame 'latter' inw-andV movement ot the'V draav rodtheaclampingj a-ws'have been) moved;` into securefclamping engagement. withy the` work'- p'iece,. the pressure: exerted: by each clamp'- ing jaw' being constant,l when! th'e'rmovement of the' draw rodl is dlisoontinued,said pres'- sure being; determined; by' the' amountv of compression ofV theI springss 371 whichz latter may be:varied,`l as above pointed. out', by adih justment. of the collars-'38'.L It will be seen that'4 the inward' movement' off thezr member 24, against which' the' springs' 37 rest, is somewhat greater. than the inward; movement of said jaw members, so.E that after engageL ment of thev jaws: with'. the: workpiece, con'- tinued? movement. of the memberA 24 com'- 'presses springs 37 and; increases the'.- tension on each jaw member. Outward or' right Vhand movement of the' draw rod 7' releases y the chuck'. in the reverse'=manner;.

Fromthe above, it willbe apparent. that theI draw rodV may be actuated' by any' deL sirable means, and that, while thefchuck is intheposition of Fig. 2, in whichxfthe jaws right',.the springs23 returning the members 1'3V and24 tothe normal: position' of Fig.' 4.

Weclaim: ...Y s

In a chuck,.an operatingrod, at setof pivotally n mounted work-centering' lingers, said fingers being urged together whenv said rodis being drawn inwardly of lthe' chuck. and ,means responsive to; further inward movement/of said rod to procure separation ofi saidv fingers.

2. Ina chuck, anoperating; rod,l a set of lingers positively away fronreach. other inv response to futher inward' movement of saidV rod.

4.. In a chuck, an operating rod,al of work-centering members, a: set ofk work-V clamping ,members, means t0 urge said` centering memberstogether and simultaneously tourge said` clamping Vmembers into clamping positionfin response to movement of said rod, and means to urgey said centering members away fromeach other, and. to: clamp said work-clamping members securely against a workpiece in4 response to further movement of said rod. i

5. In a chuck, an operating rocha; series of work-cl-amping members, means `responsive to movement ofsaidlrodl to urge said membersintfo clamping'engagement' with a: work.- piece, and means to procure av constant clampingi pressure for each member regardless of the tension onv the operating rod.,

6.. In achuck, an-operating rod, a series of work-clampingmembers, means responsive to .1

movement of said rod to urge said members into clamping'engagement'with a workpiece, said members beingheld in clamping.l position by the tension onthe rod, andmeans to procure aA constant clampingpressure vfor eachv member regardless of the tension on. the operating rod. 1

7. In aA chuck, an operating rod, work-clamping members,`means responsive to movement of said rod to urge said members into clamping engagement with a workpiece, said members beingheld in clamping engageL ment by the tension on the rod', andlvmeans to limit positively theinwardmovementv of said rod whereby to procure a constant-clamping pressure for each member regardless of the tension on the operating rod.

8. In a chuck, an operating ro-d, a' setoi' workfcentering members, a.I set ot workclamping members, meansto urge'saidfcenter.-

a series of urge said clamping members into clamping A position in response to movement of said rod,

means t0 urge said centering members away from each other and to clamp said workclamping members securely against the workpiece in response to further movement of said rod, and means to limit positively the inward movement of said rod whereby the work-clamping members exert a constant clamping pressure on said workpiece regardless of the tension on the rod.

9. In a chuck, an operating rod, a plurality of jaw members arranged to clamp against the face of a workpiece, means responsive to movement of said rod to rotate said aw members about an axis parallel t0 the aXis of the chuck and into clamping position and to move said jaw members axiallyvof the chuck to bring said members into secure clamping relation to the workpiece, and means to limit positively the movement of said rod whereby to procure a constant clamping pressure for each jaw member regardless of the tension on said rod.

10. In a chuck, an operating member, a set of pivotally mounted work-centering fingers, means responsive to movement of said operating member to urge said fingers radially into engagement with a workpiece in the chuck, and means responsive to further movement of the operating member in the same direction to withdraw said fingers from engagement `with the workpiece.

D. C. PAGE. Gr. D. SCOTT. 

